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<head><meta charset="utf-8"><title>Help fixing #80258 · t-compiler/help · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/index.html">t-compiler/help</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20fixing.20.2380258.html">Help fixing #80258</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Help%20fixing%20%2380258/near/220851292" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> osa1 <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20fixing.20.2380258.html#220851292">(Dec 24 2020 at 06:05)</a>:</h4>
<p>Hello. I have some free time this week and the next and I'd like to fix <a href="https://github.com/rust-lang/rust/issues/80258">https://github.com/rust-lang/rust/issues/80258</a> which has been bothering me for a while. Could anyone give me some pointers on where to start? I read <a href="http://wfcheck.rs">wfcheck.rs</a> and probing stuff, but I'm lost. The code is quite complicated. If someone could give me some pointers (or a relevant read list) that'd be very helpful. Thanks!</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Help%20fixing%20%2380258/near/220870751" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Joshua Nelson <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20fixing.20.2380258.html#220870751">(Dec 24 2020 at 13:46)</a>:</h4>
<p>Maybe <a href="https://rustc-dev-guide.rust-lang.org/ty.html">https://rustc-dev-guide.rust-lang.org/ty.html</a> would be helpful?</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Help%20fixing%20%2380258/near/220909137" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> osa1 <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20fixing.20.2380258.html#220909137">(Dec 25 2020 at 07:16)</a>:</h4>
<p>Thanks. I think I read most of the guide, but I still have no clue where to start. I guess I'll keep reading the auto deref stuff for now.</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Help%20fixing%20%2380258/near/220931627" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Noah Lev <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20fixing.20.2380258.html#220931627">(Dec 25 2020 at 18:43)</a>:</h4>
<p>I recommend looking at the debug log output of the code you're trying to fix. It can be very useful to help visualize what different functions are doing. Make sure that you have <code>debug = true</code> in your <code>config.toml</code>, otherwise there won't be any log output. I recommend running a command like:</p>
<div class="codehilite" data-code-language="Bash Session"><pre><span></span><code><span class="gp">$</span> <span class="nv">RUSTC_LOG</span><span class="o">=</span>path::to::module_youre_interested_in<span class="o">=</span>debug <span class="nv">RUSTC_LOG_COLOR</span><span class="o">=</span>always rustc +stage1 path/to/code-youre-trying-to-fix.rs <span class="p">&amp;|</span> less -R
</code></pre></div>
<p>It will show the log output in a pager, with colors.</p>
<p>If you're not sure what <code>+stage1</code> means, take a look at <a href="https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html#creating-a-rustup-toolchain">https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html#creating-a-rustup-toolchain</a></p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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